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46 votes

Does any organism use both photosynthesis and respiration?

tl;dr: Yes, all plants breathe.— I'm not sure whether I understand the question correctly; because all plants use respiration! Some of the organic high-energy substances produced by ...
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15 votes
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Does any organism use both photosynthesis and respiration?

Besides the unicellular organisms cited by other answers (and the fact that plants actually do respiration), there are some animals who are able to get, although indirectly, energy from photosynthesis ...
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14 votes
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Why is ATP produced in photosynthesis used to synthesize glucose?

As far as I can understand your question, you wish to know why a plant cell consumes ATP to produce glucose when it can directly use the ATP as an energy molecule. ATP is an energy currency and is ...
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12 votes

If oxygen is such a good energy source, why do plants release it?

Short answer Plants release O2, because it is not an energy source. Instead, it is used to free energy from energy-rich organic compounds. Background Plants are solar powered. They release oxygen as ...
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10 votes

What is the brain's preferred energy source? Glucose or ketones?

First of all, for those readers with less knowledge of the general principles of biology, I want to state an important, even if obvious, point: The brain doesn't "prefer" anything. Despite ...
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  • 474
8 votes

Do fish depend on plants for survival?

Yes, photosynthesis provides nearly all of the ocean's biomass and energy. The best is to study oceanic food chains and webs. It looks like there aren't enough plants in the ocean because they don't ...
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7 votes
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Why do plants create enough energy for the entire ecosystem?

Plants collect energy for themselves via photosynthesis, not for others. It is used for it's own growth and survival. It's energy is then redistributed to other organisms when either the plant dies ...
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  • 858
7 votes

Understanding entropy and the second law of thermodynamics as involved in metabolic processes

2nd law of thermodynamics states that the overall entropy of the universe cannot decrease at any time. This can also be stated as the fact that the universe naturally falls towards the lowest energy ...
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7 votes
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Do fish depend on plants for survival?

Short answer All marine life needs energy to survive and reproduce. "Heterotrophic" organisms get their energy from eating other organisms and digesting the molecules of their tissues for ...
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6 votes

Where do mushrooms get their energy from?

Mushrooms are the fruiting bodies of fungi. Fungi get their energy by decomposing dead or decaying organic material, such as fallen leaves or dung. Some background: spores of fungi germinate forming ...
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  • 371
6 votes
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Pyruvate dehydrogenase: Apparently anomalous NAD/FAD redox reaction

Summary The redox potential widely quoted in text books for the half-reaction reduction of FAD to FADH2 is indeed inconsistent with the observed direction of several reactions involving this coenzyme, ...
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  • 22.4k
5 votes

Why do (almost) all energy carriers contain adenine?

As @canadianer comments, this question is unanswerable, and it verges on being classified as ‘opinion-based’. However, because I do not find the answer from the OP appealing, I’ve set out a few points ...
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4 votes

What would happen if most the fat in your body was rapidly converted into energy in 2 minutes?

It depends, but you're going to die. Specifically, it depends on how fat you are. Even Andreas Munzer is going to die. At only 3% body fat, burning all his fat (9kcal/g) would "only" increase his ...
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  • 3,988
4 votes

Why a continuous supply of energy is needed to support a weight?

For skeletal muscles, you'll find a discussion in the Physics SE: https://physics.stackexchange.com/questions/1984/why-does-holding-something-up-cost-energy-while-no-work-is-being-done To make things ...
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4 votes

Does any organism use both photosynthesis and respiration?

Indeed several organisms can do both. Another good example following the answer from Prince of an organism that can do both photosynthesis and respiration would be cyanobacteria. Source: ...
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4 votes
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Why is a magnesium ion essential for ATP activity in enzymic reactions?

As far as I know there are two main reasons for this: promoting a nucleophilic attack In general, Mg2+ interacts with substrates through inner sphere coordination, stabilising anions or ...
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4 votes

Why do (almost) all energy carriers contain adenine?

One of the reasons why adenine is by far the most common component in energy carriers might be its less utility in DNA. Naitoh (2008) also describes this opinion. Keeping in mind the conditions on ...
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4 votes
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Does the energy from ATP hydrolysis vary among different cells?

Yes, the energy from ATP hydrolysis can vary between different cell types and condition, because it depends on several factors. Hence, you will find different values in various textbooks. First, like ...
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  • 5,595
4 votes
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How come only a handful of animals can do photosynthesis?

It is all about energy. It is estimated to take 5000 square meters of plants to feed the average person in the developed world, while the same source gives the lowest possible for a human under ideal ...
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3 votes

Why do plants create enough energy for the entire ecosystem?

Let's look at a very simple "ecosystem", cows and grass. Imagine there is 1000 kilograms of grass available. This can support about 100 kg of cow. There's your 10% figure, but mass here instead of ...
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  • 1,311
3 votes

Requirement of energy for metabolic processes

Oxygen has a high electronegativity, in other terms it really likes electrons. In this scale neon has the highest electronegativity of all elements, followed by fluorine, helium, and oxygen. ...
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  • 4,450
3 votes
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Requirement of energy for metabolic processes

I’m not quite sure which of two questions you are asking here, but as this is basic to understanding metabolism, I think an answer to both questions will be of most general utility, even if you ...
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  • 22.4k
3 votes

Requirement of energy for metabolic processes

The first reaction is catabolism. It does require some energy input in the beginning ("energy investment" of glycolysis) but ultimately leads to net energy release through "energy payoff" of ...
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3 votes
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What is ATP and why is it said to be a source of energy?

ATP is adenosine 5'-triphosphate, a molecule consisting of the base adenine attached to which is attached a ribose (at its 1 position) and (at its 5 position) three phosphates, alpha-, beta- and -...
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3 votes
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The effect of depth on net primary production in aquatic ecosystems

After a quick glance at the book "Light and Photosynthesis in Aquatic Ecosystems" by Kirk (2010), I think that the cause for the productivity dip towards the surface partially lies in photoinhibition, ...
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3 votes
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What is meant by increase in information embodied in the system?

Table 1 on the next page (p. 36) lists a number of properties for each of the three "growth forms". For information, properties include: Life history types Diversity (taxonomic & ecological) ...
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3 votes

Evidence that Attention Deficit Hyperactivity Disorder (ADHD) is caused by too much cellular ATP?

That's an interesting hypothesis - however, I am not aware of any evidence that this is the case. Importantly, there can be a lot of difference between cellular access to energy, like ATP, and the ...
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3 votes

Why do (almost) all energy carriers contain adenine?

Another reason which might have played a crucial role in preference of adenine could be its greater stability over other nucleobases. Dividing nucleobases into purines (A, G) and pyrimidines (C, T, U)...
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3 votes

Is it a valid generalization that kinases catalyse reactions involving energy transfer and utilization?

Your (original) description: a kinase helps chemically deliver or metabolize stored energy within a cell sounds a little more like what many ATPases do: they are using the energy from ATP to do ...
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3 votes
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Power consumption of a ATP synthase in Watts

There are tons of mechanistic studies of ATP synthase so you may be able to get a better answer from finding one of those. But here's a rough estimate based on thermodynamics and enzyme kinetics. The ...
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